Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnly/idempotent/closed-world, and the description adds substantial context beyond them: the data provenance (private local directory), the caveat that declarations are not measurements and passed no AIO review, the fallback mechanism, and the selection_basis/is_fallback fields. This is exactly the extra behavioral context structured fields cannot convey.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action and every sentence carries weight (caveat about non-measurement status, privacy note, fallback semantics are all needed). The first sentence is dense and parenthetical, hurting readability slightly, but there is no filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Despite having no output schema, the description enumerates the meaningful return fields (rule id, strength, declaration date, condition, aligned_with/departs_from, lookup_context.selection_basis, is_fallback) and warns that a fallback is not the organization's conclusion. For a 5-parameter tool with a nested object, nothing an agent needs to interpret results is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3, but the description adds real meaning: the condition axes determine matching and trigger a fallback when no declaration matches, and lookup_context.selection_basis reports which path was taken. That ties the nested condition object to observable output behavior rather than just restating the schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource — reading one organization's own norm file to determine which of two AIO values it declared first — and scopes it clearly to private org data rather than public Commons data. It never names the sibling aio_lookup_reference as the public-data alternative, so sibling differentiation remains implicit rather than explicit.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Clear context is given about the data source (local private org norm files under AIO_ORG_NORMS_DIR, not public Commons data), which scopes when this tool applies. It also explains the fallback path, but offers no explicit when-not guidance or named alternative to steer the agent away from it.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.